Quenching oil composition

ABSTRACT

A quenching oil composition with an improved rate of cooling for the quenching of ferrous metals comprises a major portion of a hydrocarbon mineral oil containing a minor proportion of a vicdihydrocarbyl substituted thiazole having in its 2-position a mercapto group.

Unite States atent [191 Wiipers Dec. 10, 1974 QUENCHING OIL COMPOSIITION[75] Inventor: Dale J. Wilpers, Godfrey, Ill.

[73] Assignee: Shell Oil Company, Houston, Tex.

[22] Filed: June 25, 1973 [21] Appl. No.: 373,065

[52] US. Cl 148/29, 148/206, 148/27, 252/77, 252/47.5 [51] Int. Cl. 323k35/24 [58] Field of Search 148/29, 28, 27, 20.6; 252/47, 78, 75, 71,47.5, 77

[56] References Cited UNITED STATES PATENTS 2,719,827 10/1955 Lowe252/47 3,154,490 10/1964 Rai et a1. 252/47 OTHER PUBLICATIONS ASM MetalsHandbook, Cleveland, 1948, p. 619 (TA472A3).

Stroh 148/29 Primary Examiner-Walter R. Satterfield Attorney, Agent, orFirm-Henry C. Geller 5 7 ABSTRACT A quenching oil composition with amimproved rate of cooling for the quenching of ferrous metals comprises amajor portion of a hydrocarbon mineral oil containing a minor proportionof a vic-dil'nydrocarbyl substi 6 Claims, N0 Drawings BACKGROUND OF THEINVENTION The method of hardening ferrous materials by heating them to atemperature above 1,600F and then rapidly cooling them in order toincrease the hardness is well known. The cooling step in this procedureis termed quenching. It is also known that an increase in the speed ofquenching results in increased metallic hardness. Hydrocarbon oils, inparticular mineral oils, are commonly used as quenching liquids. Butstraight mineral oils do not usually form satisfactory quench mediasince the initial rate of cooling is too slow. Hence, the development ofthe quenching oil art has been in the direction of modifying hydrocarbonoils by incorporating certain additives therein. The state of the art issuch that many various different additives have been used for thispurpose; see, for example, US. Pat. No. 3,729,417, issued Apr. 24, 1973.Illustrative of these additives for improving cooling rate areashforming materials such as oil-soluble alkali metal and- /or alkalineearth metal petroleum sulfonates, e.g., calcium, sodium, or bariumsulfonates. Such materials leave behind on the metal an ash or depositwhich affects the brightness or cleanliness of the metal surface. Thesedeposits are difficult to wipe off or remove from the metal surface.Consequently, it would be an advance in the art to have an oilcomposition containing an effective additive that facilitates rapid heatexchange between the metal and the oil composition in the heat treatingprocess, such as the hardening of steel, and to have such a compositionwhich leaves on heat-treated metal surfaces an easily removable deposit.

SUMMARY OF THE INVENTION the advantageously improved speed of quenchingachieved with the. composition of the invention, an added advantageresides in the phenomenon that any deposit left on the metallic surfacequenched with said composition is deposited in the form of an easilyremovable flake; for example, simply wiping off the metallic surfaceremoves the flaky deposit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The mineral oil base which inaddition to the additive is a critical feature of the invention musthave thermal and oxidative resistant properties capable of meeting therequirements desired in a quenching oil. Furthermore, viscosity of anoil affects its quenching properties. Usually higher viscosity oils haveslower quenching times than lower viscosity oils. In order to achievethe advantageous effects of the invention, the base oil is preferably amineral oil having a viscosity of from about I to about 200 SUS at 100Fand an aromatic content of 8-60 percent. A preferred viscosity range ofthe mineral oil is one of from about 40 to about 100 SUS at 100F. Suchoils may be illustrated by,.inter alia, a HVI 100 neutral having thefollowing properties:

Gr. API 31.6 Color NPA +1 Flash, "F 370 Pour Point, "F 0 Viscosity at100F SUS I03 Viscosity index Aromatics, 15.5 Naphthenes, 68.9 Paraffins,15.6,

a MVI 60 having the following properties:

Gr. API 30.8 Color Sayboldt +25 Flash, F 300 Pour Point, F 65 Viscosityat F SUS 58.4 Viscosity index 58 Aromatics, 8.2 Saturates, 91.4 Resins,0.4,

and the like.

The additive component required for the composition of the invention isa vicinal dihydrocarbylsubstituted thiazole having in its 2-position amercapto or sulfhydryl group and has the general formula As can be seenfrom the general formula the hydrocarbyl substituents are always onadjacent ring carbons and in the 4 and 5 positions of the thiazole ringsince the covalent bonds of the 1,2 and 3 positions of the thiazole ringare completely satisfied or filled. Although the dihydrocarbylsubstituents on the thiazole ring may be any hydrogen andcarbon-containing group such that the resultant molecule is oiLsoluble,it is preferred that these substituents be of low-molecular weight,preferably containing from one to six carbon atoms. For the purposes ofthis invention, the vicinal dihydrocarbyl substituent may be joined tocomplete a ring structure and, therefore, encompasses also the conceptof the substituent being a divalent hydrocarbylene moiety. Thus apreferred substituted thiazole has the formula where R and R are lowerhydrocarbyl, especially alkyl, groups of one to six carbon atoms or Rand R may be joined to form a divalent hydrocarbylene group of four tosix carbon atoms. For example, if the hydrocarbylene group forming thering is a butadienylene group, then R and R may be considered as.furnishing two carbon atoms each. Representative examples ofvichydrocarbyl substituted Z-mercaptothiazoles used as improvedquenching speed additives include the following:2-mercapto-4,5-dimethylthiazole, 2-mercapto- 4,5-diethylthiazole,2-mercapto-4-ethyl-5- methylthiazole,2-mercapto-4-methyl-5-propylthiazole,2-mercapto-4-methyl-5-butylthiazole, 2-mercapto-4-butyl-S-methylthiazole, 2-mercapto-4-butyl-5- ethylthiazole,2-mercapto-4-methyl-5-isoamylthiazole, 2-mercaptobenzothiazole,2-mercapto-4- methylbenzothiazole, 2-mercapto-5- methylbenzothiazole,2-mercapto-6- methylbenzothiazole, 2-mercapto-7- Most preferred are the2-mercaptobenzothiazole and the 2-mercapto-4,5-dimethylthia2ole.

The concentration of the Z-mercaptothiazole additive component requiredfor the oil compositions of the invention is a critical amount fallingwithin the range of from about 0.005 percent to about 0.04 percent byweight, based on the amount of the base mineral oil in which theadditive is dissolved. A preferred range is from about 0.01 percent toabout 0.03 percent by weight.

The compositions of the present invention, which contain as theessential additive the above-defined 2- mercaptothiazole can be furtherimproved with respect to oxidation stability by addition thereto ofphenolic antioxidants, amine antioxidants and the like.

EXAMPLE I The base mineral oil alone and the base mineral oil togetherwith the indicated concentration of additive given below and theeffectiveness thereof as improved quenching speed oils is demonstratedby testing the compositions in the GMC Magnetic Quenchometer Test. Thistest takes advantage of the fact that metals lose their magneticproperties when heated above a critical temperature called the Curiepoint and regain it when cooled. Polished nickel balls, preheated to1,625F in a muffle furnace, are dropped past a photoelectric cell into ameasured volume of oil located in a magnetic field. When the nickel ballcools to its Curie point, approximately 670F for pure nickel, it regainsits magnetic properties and is drawn to a magnet. An electric timer,which is engaged when the nickel ball passes the photoelectric cell, isautomatically stopped when the ball is drawn to the magnet. The recorded55 time in seconds is reported as the quenching time of the sample oroil being tested. The lower the quenching time reported, i.e., thesmaller the number of seconds,

' the faster is the speed of the quenching oil and the greater itscooling effectiveness. Table 1 below indicates the effectiveness of theadditives of the invention as compared with the mineral oil withoutadditives. Table 2 below containing additives not according to theinvention is included to show how additives of similar chemical contentto the Z-mercaptothiazoles of the inventions are far less effective thanthe additives of the invention in speed of quenching. The mineral oilused as base oil in Tables 1 and 2 below is a MVI 60 oil having thefollowing properties:

Gravity, lbs/gal 7.2

Color ASTM 0.5

Flash, F 300 Pour Point, "F 65 Viscosity at F SUS 58.4

Viscosity index 58 Aromatics, 8.2

Saturates, 91.4

Resins, 0.4

Table 1 GMC Quenching Test Oil Time (sec) Base oil 32 Base oil 0.01%wZ-mercaptobenzothiazole l 1 Base oil 0.03%w2-mercapto-4,5-dimethylthiazole 9 Table 2 GMC Quenching Test Oil Time(sec) Base oil 32 Base oil O. 1.25%w oil-soluble sulfur 19 Base oil0.48%w dibenzyl disulfide 17 Base oil 0.83%w tert-dodecyl mercaptan 32Base oil 0.52%w benzothiophene 32 Base oil 0.02%W benzotriazole 33 Baseoil 0.1%w hydrogenated 33 benzotriazole Base oil 0.66%w butylthiocresol30 Base oil 0.22%w thiophenol 30 Base oil 0.50%w thiobetanaphthol 27 Iclaim as my invention:

1. A quenching oil composition consisting essentially of a mineral oil,having a viscosity of from about 15 to about 200 SUS at 100F and anaromatic content of from 8 to 60 percent, and from about 0.01 to about0.03 percent by weight of a vicinal dehydrocarbylsubstitutedZ-mercaptothiazole, each hydrocarbyl substituent having from one to sixcarbon atoms.

2. The composition of claim 1 wherein said dihydrocarbyl is dialkyl.

3. The composition of claim 1 wherein said vicinal dihydrocarbylsubstituent is joined to form a divalent hydrocarbylene moiety of fourto six carbon atoms.

4. The composition of claim 1 wherein the viscosity of the mineral oilis from about 40 to about 100 SUS at 100F.

5. The composition of claim 2 wherein dialkyl is dimethyl and the2-mercaptothizole is 2-mercapto-4,5-

dimethylthiazole.

6. The composition of claim 3 wherein the hydrocarbon moiety isbutadienylene and the 2- mercaptothiazole is 2-mercaptobenzothiazole.

1. A QUENCHING OIL CMPOSITION CONSISTING ESSENTIALLY OF A MINERAL OIL,HAVING A VISCOSITY OF FROM ABOUT 15 TO ABOUT 200 SUS AT 100*F AND ANAROMATIC CONTENT OF FROM 8 TO 60 PERCENT AND FROM ABOUT 0.01 TO ABOUT0.03 PERCENT BY WEIGHT OF A VICINAL DEHYDROCARBYL-SUBSTITUTED2-MERCAPTOTHIAZOLE, EACH HYDROCARBYL SUBSTITUENT HAVING FROM ONE TO SIXCARBON ATOMS.
 2. The composition of claim 1 wherein said dihydrocarbylis dialkyl.
 3. The composition of claim 1 wherein said vicinaldihydrocarbyl substituent is joined to form a divalent hydrocarbylenemoiety of four to six carbon atoms.
 4. The composition of claim 1wherein the viscosity of the mineral oil is from about 40 to about 100SUS at 100*F.
 5. The composition of claim 2 wherein dialkyl is dimethyland the 2-mercaptothizole is 2-mercapto-4,5-dimethylthiazole.
 6. Thecomposition of claim 3 wherein the hydrocarbon moiety is butadienyleneand the 2-mercaptothiazole is 2-mercaptobenzothiazole.